基于系统动力学模型的铁路建设项目宏观经济效益评价

系统动力学采用系统仿真方法进行长期动态模拟,不受描述方程的高阶非线性限制,也不受数据不完全的影响,且处理问题直观形象,便于人机对话。本文将系统动力学与区域经济-交通系统相结合,建立了铁路建设项目宏观经济效益评价的系统动力学模型,并对模型进行了合理性检验,证明了系统动力学方法在铁路建设项目宏观经济效益评价中具有可操作性和推广价值。     

Climate reversals and the transition to agriculture

The transition to agriculture is generally acknowledged to be the economic foundation for population growth over the last 10,000 years and for modern civilization itself. Dates for pristine transitions to agriculture have become a key input into empirical work on economic growth over the very long run. We propose a model of the transition in which population and technology respond endogenously to climate. The available data on the southwest Asian case, other cases of pristine transition, and cases of non-transition are consistent with our model, but often inconsistent with rival explanations. In addition, our theory of the origins of agriculture has implications for instrumental variable strategies that can be used in empirical research on long run economic growth and development.      

中国通货膨胀动态路径的结构性转变及其启示

This article employs recently developed unknown structural break tests to investigate intrinsic structural instability in China inflation dynamics over 1981–2007. In order to capture accurately the statistical nature of potential structural beak, we use asymptotic p-value function under the non-standard distribution condition to compute the p-values for structural change tests in the presence of nuisance parameter. Empirical results suggest that China inflation dynamics witnessed a significant structural change at the end of 1994 and the instability appears to be originated from the dynamic parameters in the underlying model. The paper discusses important policy implications of the empirical findings through impulse response analyses.      

Public support to innovation and imitation in a non-scale growth model

This paper studies technology policy within a version of Jones's [1995. R&D-based models of economic growth. Journal of Political Economy 103, 759–784] non-scale R&D-based growth framework that incorporates imitation of foreign techniques. In the model, imitation is the most important source of productivity growth at the beginning of the convergence process, whereas innovation dominates later on. In addition, the transitional dynamics of the model can account for well-known empirical regularities regarding the relationship between the level of economic development and public support to technology innovation and imitation. The paper shows as well that, even though policy in Jones-type non-scale models has no long-run growth effects, level effects can be substantial.     

Factor taxation and labor supply in a dynamic one-sector growth model

This paper studies a class of AK-type growth models with factor income taxes, public capital stock and labor–leisure trade offs. While a higher capital tax rate reduces economic growth in the short run, the long-term growth effect is ambiguous and remains ambiguous even if the level of tax rate is larger than the degree of government externality. A higher labor income tax rate has ambiguous growth effects both in the short and long runs. However, if the intertemporal elasticity of substitution for labor supply is sufficiently small, a higher labor tax rate always lowers economic growth in the long run, despite the existence of productive government taxation.     

企业现金流转系统动态仿真研究

本文运用系统动力学方法分析了企业现金流转问题的基本特征。针对一特定民营企业建立了企业现金流转的系统动力模型，并在此基础上，设计四种仿真方案模拟了不同条件下企业现金流转的具体情况，以期为企业现金流以及企业的持续经营做一些有益的探索。     

基于虚拟物流的产业链整合仿真研究

提出了基于虚拟物流的产业链整合策略,构建了基于虚拟物流的产业链整合系统动力学模型,建立了系统各要素之间的因果反馈关系和模型流图,通过仿真验证了基于虚拟物流的产业链整合策略的可行性,分析了产业链整合过程中各因素对产业链整合整体收益的影响。     

苯醚甲环唑在猕猴桃中的残留动态及安全性评价

为摸清猕猴桃中有毒有害物质的残留动态,确保出口产品质量安全符合主要贸易国官方要求,本文采用气相色谱-质谱法,测定施药后不同时期苯醚甲环唑在猕猴桃果实中的残留量,并依据残留消解动态,按照欧盟和日本食品安全卫生标准,对10%苯醚甲环唑水分散粒剂的使用安全性进行评价。结果表明,苯醚甲环唑在猕猴桃中的残留量随着时间的推移逐渐下降,动态曲线符合一级动力学方程C_t=0.5359e^(-0.184t),半衰期为3.767 d,属易消解农药;按照欧盟和日本猕猴桃农药最大残留限量要求,10%苯醚甲环唑水分散粒剂按照推荐剂量单次施药,10天后采摘食用是安全的。     

裂解制乙烯动力学模型研究进展

动力学模型的准确性在模拟裂解过程的数学模型中占有重要地位,它直接影响到模拟计算结果的准确性、裂解炉的优化和先进控制水平,最终影响到乙烯生产的成本。总结了经验模型、机理模型及分子模型的建立,介绍了集总动力学模型在石油炼制生产装置中的成功应用,并针对裂解原料密度日益变重的趋势,提出了可在裂解动力学中借鉴集总动力学的准则和方法,建立裂解反应集总动力学模型,以适应发展趋势。     

Exploring the antecedents of social liabilities in CVC triads—A dynamic social network perspective

This study addresses the emergence of social liabilities by taking a social network perspective on intra- and interorganizational network configurations using the hitherto unexplored example of the corporate venture capital (CVC) triad (CVC unit, corporate business unit, and portfolio company). We investigate social capital and social liability resulting from network formation and transformation and assess their impact on interorganizational knowledge transfer and creation. Examining 12 CVC triads in Germany, we identify new antecedents of social liability, show that social capital can initially facilitate knowledge transfer and creation, and that structural and personal lock-ins may eventually turn that capital into a liability. We make key theoretical contributions to the social network and CVC literature.